failed to lazily initialize a collection of role

failed to lazily initialize a collection of role

@Entity
@Table(name="dt_user" , uniqueConstraints =
{@UniqueConstraint(columnNames="user_no"),
@UniqueConstraint(columnNames="account")}
)
public class User implements java.io.Serializable {
/**
*
*/
private static final long serialVersionUID = -8149578944942492965L;
// Fields
private long id;
private String userNo;
private Set<UserRelative> userRelatives = new HashSet<UserRelative>(0);
// Constructors
/** default constructor */
public User() {
}
@OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY, mappedBy="user")
public Set<UserRelative> getUserRelatives() {
return this.userRelatives;
}
}
above is user entity;below is another UserRelative entityFwhen want to
getUserRelatives() the problem happens .
@Entity
@Table(name="dt_user_relative")
public class UserRelative implements java.io.Serializable {
/**
*
*/
private static final long serialVersionUID = 5035928604641787267L;
// Fields
private long id;
private User user;
.....
@Id @GeneratedValue(strategy=IDENTITY)
@Column(name="id", unique=true, nullable=false)
public long getId() {
return this.id;
}
public void setId(long id) {
this.id = id;
}
@ManyToOne(fetch=FetchType.LAZY)
@JoinColumn(name="user_id")
public User getUser() {
return this.user;
}
public void setUser(User user) {
this.user = user;
}
.....
}
my problem is that the error happens when i excute this code :how can i
get getRelativeTickets() via userNo?
userDAO.getUserByNo("10001148").getRelativeTickets().size();



public User getUserByNo(String userNo) {
// TODO Auto-generated method stub
String query = "from User t where t.userNo=?1";
List<User> ls = this.findByQuery(query, userNo);
if (ls.size() > 0)
return ls.get(0);
return null;
}